JPS61164637A - Rapid dissolution of polymer in water - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to water-soluble polymers, and more particularly to methods for rapidly dissolving such polymers in water.

BACKGROUND OF THE INVENTION The use of solutions of water-soluble polymers in thickening, thickening and flocculation applications is well known. Examples of such applications include the clarification of aqueous solutions in the paper industry as well as in the treatment of sewage and industrial wastewater.

Such polymer solutions are also useful as water stabilizers and in secondary oil recovery by water flooding.

Although most of these polymers are commercially available as powders or finely divided solid particles, they are most often used in the form of aqueous solutions. This requires the solid polymeric material to be dissolved in water. Although various polymers are more or less water soluble, difficulties are often encountered in preparing aqueous polymer solutions because of slow dissolution rates and because solid polymers do not readily disperse in water.

Furthermore, the dispersion of solid polymers in water is inhibited by their tendency to agglomerate, ie to remain as agglomerates upon contact with water. A solid polymer clump immediately forms because the undissolved solid particles are encased in an outer coating of water-wet polymer that inhibits additional water from penetrating into the agglomerate. Although many of these clumps will eventually dissolve with continued stirring, it is impractical to stir the solution long enough to achieve complete dissolution.

The above problem is addressed by U.S. Reissue Patents 28,474 and 28.5.
It is described in No. 76.

The patent describes a method for rapidly dissolving water-soluble polymers in which the polymer is dispersed as a water-in-oil emulsion and then the emulsion is added to water to release the polymer into solution. Disclosure here is 5:1
Requires an oil to water ratio of ~1:10.

According to this disclosure, an emulsion containing 5-75% by weight of polymer in a dispersed state is prepared and converted into an aqueous solution. However, in practice, the upper limit of the polymer content of emulsions prepared according to the above method is much less than 75% by weight, and typically ranges from 10 to 55% by weight, depending on the properties of the particular emulsion.

Additionally, the above process practically requires a significant amount of emulsifier (e.g., 20% by weight or more based on oil) in the oil/water/polymer emulsion to provide a stable product.

Summary of the invention The present invention overcomes the above problems.

According to the invention, the water-soluble y+)ma or gum or mixture thereof is prepared by dispersing (a) &lima or gum particles in a non-aqueous liquid carrier in which they are insoluble to form a suspension. (b) adding the suspension to water with mixing to release the polymer as rapidly dissolving individual particles into the water.

Suspensions are added to water in the presence of emulsifiers or surfactants. Alternatively, the emulsifier may be added to the carrier prior to adding the polymer or gum to the liquid carrier. The liquid carrier may be soluble or insoluble in water.

The polymer or gum particles are prepared by a grinding process that does not degrade the molecular structure of the polymer or gum. No emulsifiers and/or surfactants are needed, or only in very small amounts, to provide a stable product.

Specific Description Water Soluble Polymers These poly-Ts are well known in the art and are described in numerous publications and patents. On that side, naturally occurring galactomannan gums such as guar and locust bean gum, alginates, biologically produced polymers (
(e.g. :
Examples include vinyl addition polymers such as copolymerized derivatives of. Such polymers may be nonionic, anionic, or cationic.

Gums are well known water-soluble polymers and include those described in Encyclopedia of Chemical Technology Mo 110 (2nd edition, Interscience Publishing, 1966).

The molecular weight of the above polymer is, for example, about IQ, 000 to 25,0
00. It can vary widely in the OOO range and molecular weight is not a critical parameter in the present invention.

The present invention is extremely useful for preparing aqueous solutions or dispersions of these polymers, and is particularly useful for acrylamide polymers with molecular weights exceeding 100 degrees.

Polymers with relatively high molecular weights have traditionally had great difficulty in dissolving in water and have tended to form very viscous solutions even at relatively low concentrations. The polymer may be produced by any suitable method of carrying out a polymerization reaction. Therefore, solution polymerization, suspension polymerization or emulsion polymerization techniques may be used.

As used herein, "Polymer J" includes polymers and gums that are soluble in water to a significant extent. Polymers are solids but can contain significant water content.

The present invention [having a polymer concentration within the range of 11 to 10% by weight, preferably within the range of 0.2 to 2.0% by weight]
Aqueous solutions of water-soluble synthetic or natural polymers can be rapidly produced.

The rate of polymer dissolution into the milling process water is a function of surface area and therefore particle size. The polymers produced by most manufacturing processes are in the form of powders or bulk agglomerates. The large particle size minimizes handling and dust generation problems and reduces the formation of gel particles in the aqueous layer. However, large particle size increases dissolution time when dry particles are added directly to water.

Therefore, it is desirable to comminute the polymer particles by grinding, abrading, or slicing techniques to develop a large surface area that facilitates rapid dissolution when the polymer particles come into contact with water.

The preferred particle size of the polymer or gum is determined by the desired degree of improvement in dissolution rate in water and is generally less than 100 microns, preferably less than 70 microns. Small particle size also promotes suspension stability.

Many of the polymers compatible with this method undergo molecular structure degradation due to heat generation during grinding. For such heat-sensitive polymers, grinding without molecular degradation can be achieved through cryogenic grinding, such as by the use of carbon dioxide acid or liquid nitrogen, to reduce the temperature of the polymer prior to and during the grinding or slicing process. can be realized. Cryogenic milling is also beneficial for polymers that become plastic or viscous at the temperatures encountered in the ambient milling process.

Such cryogenic grinding processes use grinding equipment such as that sold by Pulverizing Machinery Company under the trade name MikroPtII J. Grinding equipment using a slicing action, such as that sold by Ursier Latrice under the trade name Com1trol J, may additionally be used to further reduce particle size in the polymer suspension itself. Equipment is selected to protect the polymer from molecular degradation and to produce the desired rate of dissolution when the polymer suspension is introduced into the water with mixing.

From a suspension industrial perspective, it is advantageous for the polymer suspension to be stable so that minimal or no agitation of the storage suspension is required and for the polymer concentration to be as high as possible to minimize shipping costs. be. According to the present invention, suspensions can be produced having kilima solids concentrations as high as 70-751X weight percent, depending on particle size, carrier viscosity, and the effect of the suspending or dispersing agent on the suspension viscosity. ! The preferred polymer solids concentration range in the V suspension is about 50-70% by weight. Suspension stability is improved by micronization of the polymer or gum and by a high viscosity liquid carrier. Additionally, the carrier may be treated with suitable thickening agents, dispersants, suspending agents, or viscosity modifiers well known in the art.

A particularly advantageous method of increasing stability when using a hydrocarbon oil carrier is to use a hydrocarbon oil carrier such as the inoctylphenoxypolyethoxyethanol product sold by Rohm and Haas under the trade name Triton X-10oJ. When this oil-in-water emulsifier is added to a hydrocarbon carrier,
It is said that it enhances the dissolution of the polymer by increasing the stability of the suspension and emulsifying the hydrocarbon in the water in which the polymer will later be dissolved, thus exposing the oil-free polymer surface to the water. It accomplishes two functions.

The polymer must not be soluble in the liquid carrier and the carrier must be substantially free of water.

However, the liquid carrier may be water-soluble or water-insoluble.

Since the liquid carrier is substantially free of water, no water-in-oil emulsion is formed, in contrast to the methods of the first two patents mentioned. Although solid polymers have a significant water content, this water content does not result in the formation of water-in-oil emulsions.

Examples of suitable hydrocarbon oil carriers include Conoco's [
LOPsJ (low odor paraffin solvent) and Exxon's [
Paraffinic base oils such as Fazam J may be mentioned.

Exxon's IgoparM (a deodorized high purity isoparaffinic material) is also suitable, as are the hydrocarbon liquids disclosed in the aforementioned patents.

Water-soluble or water-dispersible carriers in which the polymer is insoluble under practical conditions may also be used to form the polymer suspension. If the liquid carrier is water soluble, no surfactant is necessary. Examples of such carriers are higher alcohols, glyfurs, glycol ethers, and the like.

Polymer Dissolution When a & lima-containing suspension of the type described herein is dispersed in water, the polymer rapidly dissolves in the water.

Polymer-containing suspensions produce aqueous solutions in a very short time compared to the amount of time required to dissolve conventional solid form polymers.

The polymer-containing suspension is dispersed in water by any suitable means. When a water-insoluble carrier is used, a most convenient expedient is to use a surfactant that is present either in the polymer-containing suspension or in the water in which the polymer is to be dissolved. Surfactants rapidly emulsify the carrier in water (forming an oil-in-water emulsion), thus promoting the formation of an aqueous polymer solution. When this technique is used to convert a polymer-containing suspension to an aqueous solution, the amount of surfactant present in the water is based on the polymer (L(M~3
It can vary over a range of 0%. Based on carrier1
Good conversions often occur within the range of 0-8%.

Preferred surfactants for use with polymer suspensions in hydrocarbon liquid carriers are hydrophilic and water soluble. Any cationic, anionic or nonionic hydrophilic substance may be used as the surfactant, although it is best to choose a surfactant whose ionic properties do not interact with the properties of the dissolved polymer.

In addition to using water-soluble surfactants with hydrocarbon carriers, other species of surfactants such as silicones, clays, etc. may also be used. This is because, in the case of certain species, they tend to emulsify hydrocarbon carriers even though they are not themselves water-soluble.

Using this method, various polymers can be combined into a single suspension, thus improving the technical performance of the mixture when multiple polymers in suspension are dissolved in water as a co-dissolution. be done. Examples of such combinations include, for example, nonionic polyacrylamide and cationic or anionic polyacrylamide copolymer, anionic polyacrylamide and biological polysaccharide, polyethylene oxide and nonionic polyacrylamide, polyethylene oxide and Contains cationic to anionic polyacrylamide copolymers or biopolysaccharides and galactomannan gum.

Examples 1-26 To illustrate the invention, Examples 1-26 are summarized in the table below. A number of suspensions have been prepared containing various water-soluble polymers and using various types of liquid carriers. The suspension was then converted to an aqueous polymer solution using various conversion techniques, and the time required to dissolve the polymer was compared to the time required to dissolve the dry polymer or gum in its commercially available form. In all cases, a significant reduction in dissolution time was observed and the usual problems encountered in handling and dispersing dry polymers or gums were eliminated.

In such instances where the liquid carrier is a hydrocarbon oil,
Hydrocarbon oil is #2 diesel oil (50%) and Faxa
m22 (50%) (Fax
am 22 is the trade name of a general-purpose paraffin base oil sold by Exxon). In those instances where a surfactant was present, the surfactant was Triton X-100 and was present in the suspension or water in an amount calculated to give a nominal surfactant content by weight based on the product. . If an emulsifier is used, the emulsifier is Triton X-10
0 and was present in the suspension or water in an amount calculated to give a nominal 2 weight surfactant content based on the product. If an emulsifier is used, the emulsifier is Tr
ltonX-100 and was present in the suspension in an amount calculated to give an emulsifier concentration of about 2% by weight based on the suspension. ′°”Example 26
In, a small amount (approximately 1% by weight based on the suspension) B
@5 tons 8D-1 (clay dispersant sold by NL Industries) was added to the suspension to improve stability.

All percentages of carrier and polymer or gum are based on the total suspension. In six cases, sufficient suspension was mixed with water to give an aqueous polymer concentration of approximately α2 weight meters.

Example 27 A sample of dry polyacrylamide (400-800 micron particle size) was dissolved directly in water with stirring to form an alpha 15 wt% solution. Dissolution required 75 minutes of mixing. Solution viscosity was measured as 256 cps.

Two samples of polymer from the same batch were ground to 70μ using the cryogenic method and the ambient temperature grinding method in an air fractional mill (ACM) type grinder, respectively. Crushing is done by grinding. Both ground samples were suspended in a surfactant-containing hydrocarbon oil and converted to an aqueous solution according to the procedure of Example 4.

Both polymer samples dissolved within 10 minutes.

The polymer aqueous solution (A15 extra weight polymer) from the above two types of pulverized products was 24.2 eps (low temperature pulverized) and 14,
Each had a viscosity of 2 cps (ambient temperature grind).

This example demonstrates the advantage of cryogenic milling over ambient temperature milling, which is less likely to disrupt molecular structure.

Claims (1)

[Scope of Claims] 1) A method for rapidly dissolving a water-soluble polymer or gum in water, the method comprising: (a) crushing the polymer or gum under conditions that do not substantially destroy the molecular structure; (b) dispersing the particles in a substantially water-free liquid carrier in which the polymer or gum is substantially insoluble to form a dispersion; and (c) dispersing the suspension. adding a liquid to water with thorough mixing to disperse and rapidly dissolve the particles in the water. 2) The liquid carrier is a hydrocarbon oil and the hydrophilic emulsifier or polymer or gum is to be dissolved in the suspension so as to form an oil-in-water emulsion in step (c) to promote rapid dissolution. 2. A method according to claim 1, wherein the method is in water. 3) A method according to claim 1, wherein the particles are insoluble in the liquid carrier and the liquid carrier is soluble or easily dispersible in the water to which the suspension is added. 4) The method of claim 1, wherein the polymer or gum comprises about 10-70% by weight of the suspension. 5) A method according to claim 1, wherein a dispersion aid or suspending agent is present in the liquid carrier. 6) The method according to claim 1, wherein the polymer or gum comprises one or a mixture of two or more kinds. 7) The method of claim 1, wherein the particles have a size of about 70 microns or less. 8) A method according to claim 1, wherein the grinding step is carried out by cold grinding. 9) The method of claim 1, wherein the particles are substantially insoluble in a liquid carrier and the liquid carrier is soluble in water. 10) The polymer or gum is about 10-70% by weight of the suspension.
10. The method according to claim 9, which comprises: 11) The method according to claim 9, wherein the polymer or gum is a mixture of one or more kinds. 12) The method of claim 9, wherein the particles have a size of about 70 microns or less. 15) A method according to claim 9, wherein the grinding step is carried out by cold grinding. 14) A method for rapidly dissolving a polyacrylamide polymer in water, comprising the steps of: (a) preparing fine particles of polyacrylamide by grinding a polyacrylamide polymer under cryogenic grinding conditions; and (b) dissolving the particles. dispersing the polymer in a substantially water-free liquid carrier in which the polymer is substantially insoluble to form a dispersion; (c) adding the suspension to water with thorough mixing to submerge the particles in the water; A dissolution method comprising the steps of dispersing and rapid dissolution. 15) The liquid carrier is a hydrocarbon oil and the hydrophilic emulsifier is in suspension or in the water in which the polymer is to be dissolved so as to form an oil-in-water emulsion in step (c) to promote rapid dissolution. First existing claim
The method described in Section 4. 16) The method of claim 14, wherein the particles are insoluble in the liquid carrier and the liquid carrier is soluble or easily dispersible in the water to which the suspension is added. 17) The method of claim 14, wherein the polymer comprises about 10-70% by weight of the suspension. 18) A method according to claim 14, wherein a dispersion aid or suspending agent is present in the liquid carrier. 19) The method of claim 14, wherein the particles have a size of about 70 microns or less. 20) Claim 1, wherein the particles are substantially insoluble in a liquid carrier and the liquid carrier is soluble in water.
The method described in Section 4. 21) The method of claim 20, wherein the polymer comprises in the range of about 10-70% by weight of the suspension. 22) The method of claim 20, wherein the particles have a size of about 70 microns or less.